Change search
Refine search result
12 1 - 50 of 70
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Andersson, Roger
    et al.
    Luleå tekniska universitet.
    Magnusson, Claes
    Schedin, Erik
    Luleå tekniska universitet.
    Using stainless steel for energy absorbing components in automobiles2001In: Innovations in processing and manufacturing of sheet materials: proceedings / the Second Global Symposium on Innovations in Materials Processing and Manufacturing: Sheet Materials, held at the 2001 TMS annual meeting, February 11 - 15, 2001, New Orleans, Louisiana / [ed] Mahmoud Y. Demeri, Warrendale, Pa: Minerals, Metals & Materials Society, 2001, p. 97-110Conference paper (Refereed)
    Abstract [en]

    To increase the crash performance in automobiles it is necessary to use new techniques and materials. To produce energy absorbing components the material should have high yield strength, high elongation to fracture and strong work hardening. The total work a component absorbs during impact is the area under the stress-strain curve for unit material volume. This has lead to an interest in high strength stainless steels as crash safety components in automobiles due to their excellent material properties. The material performance of different stainless grades has been evaluated through intrinsic and simulative tests. A stainless steel bumper beam has been optimised for a VOLVO car and comparisons have been made with the present application. Simulations have been done and verified by experiments.

  • 2.
    Andersson, Roger
    et al.
    Luleå tekniska universitet.
    Powell, John
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Magnusson, Claes
    Fem-simulation of forming and subsequently impact behaviour of a stainless steel component2005In: Proceedings of the 8th ESAFORM Conference on Material Forming / [ed] Dorel Banabic, Bucharest: The Romanian Academy Publishing House , 2005, Vol. 1, p. 265-268Conference paper (Refereed)
  • 3. Andersson, Roger
    et al.
    Schedin, Erik
    Magnusson, Claes
    Ocklund, J.
    Persson, A.
    Stainless steel components in automotive vehicles2004In: Stainless Steel World, ISSN 1383-7184, Vol. 16, no 1, p. 34-37Article in journal (Other academic)
    Abstract [en]

    Components linked to crash safety in automotive vehicles are required to transmit or absorb energy. The energy absorbing capability of a given component depends on a combination of geometry, material properties and loading conditions. Increased crash performance can be obtained by using materials with higher yield strength and relatively high elongation to fracture. These demands have led to increasing interest in the use of high strength stainless steels due to their relatively high elongation to fracture and good formability. To increase knowledge of the formability and forming behaviour of these materials, several components from current and prototype vehicles have been made using high strength stainless steels at Volvo Cars Body Components, Olofstrom, Sweden. These were subsequently analysed in close collaboration with the Division of Manufacturing Systems Engineering at Lulea University of Technology, Sweden.

  • 4.
    Andersson, Roger
    et al.
    Luleå tekniska universitet.
    Schedin, Erik
    AvestaPolarit Inc..
    Magnusson, Claes
    Ocklund, Jonny
    Volvo Car Corporation.
    Persson, Arne
    Volvo Car Corporation.
    The applicability of stainless steels for crash absorbing components2002In: ACOM : Avesta Sheffield corrosion management and application engineering, ISSN 1101-0681, Vol. 3-4, p. 7-12Article in journal (Other academic)
    Abstract [en]

    To increase crash performance in automotive vehicles it is necessary to use new techniques and materials. Components linked to crash safety should transmit or absorb energy. The energy absorbing capability of a specific component is a combination of geometry and material properties. For these components the chosen material should have high yield strength and relatively high elongation to fracture. These demands have led to increasing interest in the use of high strength stainless steels. The relative performance of three high strength carbon steels and two high strength stainless steel grades was evaluated through intrinsic and simulative tests. The rear bumper for a Volvo Car model in current production was manufactured using the five sheets tested to verify formability and behaviour under load. The bumpers were clamped in a rig that allowed quasi-static impact tests to be made. The energy absorbing capabilities were evaluated by measuring force versus displacement during the impact test.

  • 5.
    Andersson, Roger
    et al.
    Luleå tekniska universitet.
    Syk, M.
    Powell, John
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Magnusson, Claes
    Formability behaviour of meta-stable stainless steels2005In: Proceedings of the 8th ESAFORM Conference on Material Forming / [ed] Dorel Banabic, Bucharest: The Romanian Academy Publishing House , 2005, Vol. 1, p. 359-362Conference paper (Refereed)
  • 6.
    Asnafi, Nader
    et al.
    Luleå tekniska universitet.
    Magnusson, Claes
    On formability of sheet aluminium1990In: Sheet metals in forming processes: 16th biennial congress IDDRG, open sessions, Borlänge, June 11 - 13, 1990 ; congress proceedings, reports, posters, Borlänge: Materials Center, HTM , 1990, p. 81-91Conference paper (Refereed)
    Abstract [en]

    Sheet metal behaves differently for different stress and strain ratios. For instance, the material tolerates less deformation at plane strain compared with uniaxial tension. Hill's yield criteria can be used to describe sheet material's deformation behavior. Hill's original yield criterion for plane stress, assuming that there is no planar anisotropy is given. The equation shows better agreement with experimental results when r > 1 (steel 4010), while there is no agreement with experimental results when r < 1 (Al-5052). Hill proposed, therefore, a new yield criterion, which is given. The value of a can be determined by comparing the experimental work-hardening characteristics for uniaxial tension and balanced biaxial tension; 1 < = a < = 2. For soft Al, having an average r-value of 0.723, the value of a has been found to be 1.8. The parameter a has its greatest effect at balanced biaxial tension. Graphs

  • 7.
    Borgström, Robert
    et al.
    Luleå tekniska universitet.
    Magnusson, Claes
    Flexibel laserbearbetning: begrepp, systembeskrivning, verktygsväxling, industriella tillämpningar1992Report (Other academic)
  • 8.
    Ducharme, R.
    et al.
    University of Essex.
    Kapadia, Phiroze D.
    University of Essex.
    Lampa, C.
    Luleå tekniska universitet.
    Ivarsson, Anders
    Luleå tekniska universitet.
    Powell, John
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Magnusson, Claes
    Effects of different shielding gas compositions on the process of cw CO2 laser welding in the hyperbaric range1996In: XI International Symposium on Gas Flow and Chemical Lasers and High-Power Laser Conference / [ed] Denis R. Hall; Howard J. Baker, Bellingham, Wash: SPIE - International Society for Optical Engineering, 1996, p. 530-533Conference paper (Refereed)
    Abstract [en]

    A continuous carbon-dioxide laser of 1.35 kW has been used to study the welding of 5 mm thick stainless steel for pressures ranging from 0.1 to 0.8 MPa in increments of 0.1 MPa. Experimental data, including penetration depths, weld widths, and in some cases weld pool profiles, has been obtained for each value of the pressure using different mixtures of argon and helium shielding gases. In a previous paper it has been reported that keyhole welding could not be carried out for pressures significantly in excess of atmospheric pressure using pure argon and nitrogen shielding gases, but that the process was possible at pressures up to 0.8 MPa using helium. In the present paper the critical pressure for keyhole welding is determined as a function of the mixed shielding gas composition. The laser material interaction is analyzed by solving the heat conduction equation with line and point heat sources representing the keyhole and plume respectively. The line source strength is itself calculated from consideration of the inverse bremsstrahlung and Fresnel absorption processes in the keyhole. It is concluded that successful laser welding in the hyperbaric range crucially hinges on good plume control through the effective delivery of an appropriate shielding gas mixture.

  • 9.
    Engström, Hans
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Magnusson, Claes
    High power laser materials processing in the nordic countries1997In: Proceedings of the 6th Nordic Laser Material Processing Conference, Luleå, Sweden, August 27-29, 1997 / [ed] Claes Magnusson; Hans Engström, Luleå: Luleå tekniska universitet, 1997, p. 6-8Conference paper (Refereed)
  • 10.
    Engström, Hans
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Magnusson, Claes
    Sarady, Istvan
    Mätning av yttemperaturen hos transmissiv optik vid laserbearbetning1990Report (Other academic)
  • 11.
    Engström, Robert
    et al.
    Luleå tekniska universitet.
    Magnusson, Claes
    Engström, Hans
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Flexibla laserbaserade produktionsceller1991Report (Other academic)
  • 12.
    Flinkfeldt, Jan
    et al.
    Luleå tekniska universitet.
    Magnusson, Claes
    Ytimpregnering med laser1986Report (Other academic)
  • 13. Forsman, Tomas
    et al.
    Kaplan, Alexander
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Powell, John
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Magnusson, Claes
    Initiation and termination phenomena in laser welding of aluminum2000In: Journal of laser applications, ISSN 1042-346X, E-ISSN 1938-1387, Vol. 12, no 2, p. 81-84Article in journal (Refereed)
    Abstract [en]

    This article investigates a defect problem related to laser welding of tailored aluminum blanks. During the initial few millimeters of welding the weld was intermittent. By applying an analytical line source model the weld was shown to experience overheating close to the starting edge. This overheating was reduced by ramping the power during the initial 100 mm and this made the defects disappear. Al sheets of 0.1mm thickness with milled edges were butt welded and bead-on-plate welded in the present investigation.

  • 14.
    Forsman, Tomas
    et al.
    Luleå tekniska universitet.
    Lampa, Conny
    Luleå tekniska universitet.
    Powell, John
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Magnusson, Claes
    Prediction of the cross-sectional geometry of Nd:YAG laser welds in aluminum alloys2000In: Proceedings of the Laser Materials Processing Conference: [November 15 - 18, 1999, Catamaran Resort Hotel, San Diego, CA, USA], [presented at] ICALEO '99 / [sponsored by Laser Institute of America]. Co-chairs: Paul Denney ..., Orlando, Fla.: Laser institute of America , 2000, p. E156-E165Conference paper (Refereed)
    Abstract [en]

    This paper describes an analytical model for determining the geometry of laser welds. An earlier model by Lampa and Kaplan (1997), for CO2 laser welding of stainless steel, has been further developed to cover Nd:YAG laser welding of aluminium alloys. This analytical work was followed by experimental verification using a 4 kW Nd:YAG laser. The model was found to be accurate over a wide range of process parameters

  • 15. Forsman, Tomas
    et al.
    Magnusson, Claes
    Powell, John
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Nd:YAG laser welding of coated aluminium sheet with a new dry lubricant film1998In: Svetsen, ISSN 0039-7091, Vol. 57, no 3, p. 10-12Article in journal (Refereed)
    Abstract [en]

    Trials are reported of the Nd:YAG laser welding of sheet of thickness about 1 mm in two aluminium alloys (AA-5182 (Al, 4.0-5.0%Mg) and AA-6016 (Al, 0.3-0.6%Mg, 1.0-1.5%Si)) coated with "Drylube" dry lubricant (some with zinc passivation first). Effects were investigated of welding conditions (constant or pulsed operation, gap of 0.0-0.3 mm) on porosity, penetration, and microcracking at the fusion boundary. Weld cross-sections are presented. Results are given also of hardness and tensile tests.

  • 16. Forsman, Tomas
    et al.
    Powell, John
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Lampa, Conny
    Luleå tekniska universitet.
    Kaplan, Alexander
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Magnusson, Claes
    Nd:YAG laser welding of aluminium: factors affecting absorptivity1999In: Lasers in engineering (Print), ISSN 0898-1507, E-ISSN 1029-029X, Vol. 8, no 4, p. 295-310Article in journal (Refereed)
    Abstract [en]

    This paper investigates the factors affecting the absorptivity during Nd:YAG laser keyhole welding of a 6xxx aluminum alloy. The influence of surface condition on absorption is shown to be negligible. Experimental absorption measurements by calorimetry are compared to analytical absorption values using a simple model based on Fresnel absorption during multiple reflections in the keyhole.

  • 17.
    Forsman, Tomas
    et al.
    Luleå tekniska universitet.
    Powell, John
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Magnusson, Claes
    A review of laser welding of low density structural materials: (Alloys of titanium, aluminium, magnesium and polymers)1997In: Proceedings of the 6th Nordic Laser Material Processing Conference, Luleå, Sweden, August 27-29, 1997 / [ed] Claes Magnusson; Hans Engström, Luleå: Luleå tekniska universitet, 1997, p. 44-57Conference paper (Refereed)
  • 18.
    Forsman, Tomas
    et al.
    Luleå tekniska universitet.
    Powell, John
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Magnusson, Claes
    Nd:YAG laser lap welding of coated aluminum alloys1997In: Proceedings of the Laser Materials Processing Conference: [November 17 - 20, 1997, Catamaran Resort Hotel, San Diego, California, USA] / [ed] Rémy Fabbro, Orlando, Fla: Laser institute of America , 1997, p. G113-G120Conference paper (Refereed)
    Abstract [en]

    This experimental program investigated the production of lap welds between 1 mm thick sheets of aluminium alloys 5182 and 6016 which had previously been coated with Drylube. (Drylube is a polymer based coating approx1 mu m thick which improves the formability of the aluminium alloy sheet). Successful welds were produced using a 2.5 kW Nd:YAG laser in conjunction with a 0.6 mm optical fibre. It was discovered that there is an optimum gap width between the two sheets which gives the best weld quality and strength. Pulsed and CW laser welds were produced and compared with respect to porosity and surface profile, etc

  • 19.
    Forsman, Tomas
    et al.
    Luleå tekniska universitet.
    Powell, John
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Magnusson, Claes
    Process instability in laser welding of aluminum alloys at the boundary of complete penetration2001In: Journal of laser applications, ISSN 1042-346X, E-ISSN 1938-1387, Vol. 13, no 5, p. 193-198Article in journal (Refereed)
    Abstract [en]

    Intrinsic instabilities in the depth of penetration achieved when laser welding aluminum alloys were investigated in this article. Four types of weld pool configuration, resulting in different welds, were identified, only two of which are associated with full penetration. A simple phenomenological explanation of the unstable welding process at the boundary of complete penetration was proposed. The nature and cause of the instabilities were discussed and suggestions were offered for process control. Materials used: AA6016 aluminum alloy.

  • 20.
    Gedda, Hans
    et al.
    Luleå tekniska universitet.
    Powell, John
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Wahlström, G.
    Li, W-B
    Luleå tekniska universitet.
    Engström, Hans
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Magnusson, Claes
    Energy redistribution during CO2 laser cladding2001In: Congress proceedings: Laser Materials Processing Conference; Laser Microfabrication Conference [at] ICALEO 2001, 20th International Congress on Applications of Lasers & Electro-Optics : October 15 - 18, 2001, Adam's Mark Hotel, Jacksonville, Florida, USA / [ed] Xiangli Chen, Orlando, Fla: Laser institute of America , 2001, p. 549-558Conference paper (Refereed)
    Abstract [en]

    This paper examines the factors that effect the efficiency of the CO sub 2 -laser powder cladding process. By theoretical calculation and experimental work it has been possible to identify how much of the original laser energy contributes to the cladding process and how much is lost to the surrounding environment by reflection, radiation, convection etc. Every aspect of energy redistribution has been analysed and quantified and this has lead to a deeper understanding of the process. The paper concludes with a number of suggestions for improving the efficiency of blown powder laser cladding

  • 21.
    Gedda, Hans
    et al.
    Luleå tekniska universitet.
    Powell, John
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Wahlström, G.
    Duroc AB.
    Li, W-B
    Luleå tekniska universitet.
    Engström, Hans
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Magnusson, Claes
    Energy redistribution during CO2 laser cladding2002In: Journal of laser applications, ISSN 1042-346X, E-ISSN 1938-1387, Vol. 14, no 2, p. 78-82Article in journal (Refereed)
    Abstract [en]

    This article examines the factors that effect the efficiency of the CO sub 2 -laser powder cladding process. By theoretical calculation and experimental work it has been possible to identify how much of the original laser energy contributes to the cladding process and how much is lost to the surrounding environment by reflection, radiation, convection, etc. Every aspect of energy redistribution has been analyzed and quantified and this has led to a deeper understanding of the process. The article concludes with a number of suggestions for improving the efficiency of blown powder laser cladding.

  • 22.
    Ilar, Torbjörn
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Magnusson, Claes
    Development of a flexible manufacturing system with high power laser1986In: Proceedings of the 5th International Conference on Flexible Manufacturing Systems: 3-5 November 1986, Stratford-upon-Avon, U.K / [ed] Keith Rathmill, Bedford :: IFS , 1986, p. 343-52Conference paper (Refereed)
    Abstract [en]

    It is a great opportunity for the Laser Research Group at the University of Lulea to participate in the development of a flexible manufacturing system including a laser welding cell, in co-operation with a small Swedish company. The laser research group have, in the progress of the system build-up, contributed with welding tests of the work-pieces, design of a flexible laser welding cell including fixture units and material handling equipment. We have also given our recommendation of the purchase of a laser-system. This paper presents the planning of this flexible laser processing cell, where the additional advantages with laser welding and flexibility are the main objectives with the installation.

  • 23.
    Ivarson, A.
    et al.
    Luleå tekniska universitet.
    Powell, John
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Flinkfeldt, Jan
    Luleå tekniska universitet.
    Magnusson, Claes
    The effects of alloying elements on the laser cutting process1998Report (Other academic)
  • 24.
    Ivarson, A.
    et al.
    Atlas Copco Rock Drills AB.
    Powell, John
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Ohlsson, L.
    Luleå tekniska universitet.
    Magnusson, Claes
    Reflection phenomena in Co2 laser cutting1997In: Proceedings of the 6th Nordic Laser Material Processing Conference, Luleå, Sweden, August 27-29, 1997 / [ed] Claes Magnusson; Hans Engström, Luleå: Luleå tekniska universitet, 1997, p. 16-24Conference paper (Refereed)
  • 25.
    Ivarson, Anders
    et al.
    Luleå tekniska universitet.
    Magnusson, Claes
    Powell, John
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Laser cutting of steels: analysis of the particles ejected during cutting1992In: Welding in the World, ISSN 0043-2288, E-ISSN 1878-6669, Vol. 30, no 5-6, p. 116-125Article in journal (Refereed)
    Abstract [en]

    The particles ejected during the CO sub 2 laser cutting of mild and stainless steel were examined by electron microscopy, energy dispersive X-ray analysis and optical microscopy. The material leaves the cut zone as partially oxidized droplets which range in size from 50-500 mu m in diameter. When cutting mild steel approx 50% of the Fe is converted to FeO during the cutting process, whereas for stainless steel approx 30% of the Fe is oxidized to Fe sub 2 O sub 3 . The mild steel particles were found to exist in five distinct oxidation stages whereas the stainless steel particles fell into four groups containing not only Fe sub 2 O sub 3 but also Cr sub 2 O sub 3 and NiO.

  • 26.
    Ivarson, Anders
    et al.
    Luleå tekniska universitet.
    Powell, John
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Kamalu, J.
    University of Dundee, Department of APEME.
    Magnusson, Claes
    Oxidation dynamics of laser cutting of mild steel and the generation of striations on the cut edge1994In: Journal of Materials Processing Technology, ISSN 0924-0136, E-ISSN 1873-4774, Vol. 40, no 3-4, p. 359-374Article in journal (Refereed)
    Abstract [en]

    Over the past two decades CO2 laser cutting has grown from an obscure laboratory technique into an important branch of manufacturing engineering. The most commonly cut materials are steels and a great deal of industrial and scientific research has been carried out on the laser-material interactions that generate a cut. This paper concentrates on the phenomena which give rise to a cyclic cutting event when a CO2 laser in conjunction with an oxygen jet is used to cut mild steel. The nature of the cut edge striation produced by the cyclic oxidation reaction is explained thoroughly and a possible oxidation cycle is postulated. It is demonstrated that the key to understanding the cyclic nature of the cutting event is the self-limiting nature of the oxidation of the steel in the cut zone

  • 27.
    Ivarson, Anders
    et al.
    Luleå tekniska universitet.
    Powell, John
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Magnusson, Claes
    Laser oxygen cutting of stainless steel with powder injection or metal tape feed1997In: Lasers in engineering (Print), ISSN 0898-1507, E-ISSN 1029-029X, Vol. 6, no 3, p. 235-245Article in journal (Refereed)
    Abstract [en]

    This paper investigates the development and automation of an idea originally published by Arata et al.. If a layer of mild steel is placed over a stainless steel sheet during laser cutting, the cut edge quality of the stainless steel will be greatly improved. This present work demonstrates that similar cut edge improvements are possible by passing a mild steel tape through the laser beam above the stainless steel work piece during cutting

  • 28.
    Ivarson, Anders
    et al.
    Luleå tekniska universitet.
    Powell, John
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Magnusson, Claes
    Role of oxidation in laser cutting stainless and mild steel1991In: Journal of laser applications, ISSN 1042-346X, E-ISSN 1938-1387, Vol. 3, no 3, p. 41-45Article in journal (Refereed)
    Abstract [en]

    This paper gives the results of a detailed examination of the particles ejected from the cut zone during CO2 laser cutting of mild and stainless steels. Cuts were carried out over a range of material thickness at the optimum speed for each at a laser power of 900 Watts. Particles ejected from the cut zone were collected and analyzed to establish their chemical and physical characteristics. Analysis techniques included Scanning Electron Microscopy, wet chemical analysis, optical microscopy, metallography and particle sizing. The results from this extensive analysis have enabled the authors to estimate the heat generated by the oxidation process during cutting of both mild and stainless steels.

  • 29.
    Ivarson, Anders
    et al.
    Luleå tekniska universitet.
    Powell, John
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Magnusson, Claes
    Role of oxygen pressure in laser cutting mild steels1996In: Journal of laser applications, ISSN 1042-346X, E-ISSN 1938-1387, Vol. 8, no 4, p. 191-196Article in journal (Refereed)
    Abstract [en]

    This paper presents the results of an experimental program investigating the effects of using high pressure oxygen as assist gas in combination with a pulsed laser while cutting medium thick mild steel plates. It was discovered that if the pulse conditions are optimized, the maximum cutting speed for a set average laser power could be increased by up to 10% compared to low oxygen pressure continuous wave (CW) laser cutting. The assist gas was found to have two optimum pressure ranges between which the material suffered from burning on the cut edge. The paper presents a phenomenological model to explain the changes in cut front dynamics as the oxygen pressure is increased and the role of pulsing in suppressing edge burning

  • 30.
    Ivarson, Anders
    et al.
    Luleå tekniska universitet.
    Powell, John
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Ohlsson, L.
    Magnusson, Claes
    Optimisation of the laser cutting process for thin section stainless steels1992In: Proceedings of the laser materials processing symposium: ICALEO '91 ; [November 3 - 8, 1991, San Jose, California, U.S.A.] / [ed] Akira Matsunawa,; Eckhard Beyer; Edward A. Metzbower, Orlando, Fla: Laser institute of America , 1992, p. 211-220Conference paper (Refereed)
    Abstract [en]

    This paper presents the results of an experimental program investigating the effects of using a pulsed laser for laser-oxygen cutting of thin section stainless steels. It was discovered that if the pulse conditions are optimised, the maximum cutting speed for a set average laser power could be increased by up to 15%. This increase in cutting speed was made possible by a change in the material removal mechanism in the cut zone. The steady state melting-oxidation-ejection process was replaced by a periodic expulsion of melt as a result of small 'explosions' caused by the spike at the beginning of each laser pulse

  • 31.
    Lampa, Conny A.
    et al.
    Luleå tekniska universitet.
    Kaplan, Alexander
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Resch, M.
    Vienna University of Technology.
    Magnusson, Claes
    Fluid flow and resolidification in deep penetration laser welding1998In: Lasers in engineering (Print), ISSN 0898-1507, E-ISSN 1029-029X, Vol. 7, no 3-4, p. 241-253Article in journal (Refereed)
  • 32.
    Lampa, Conny
    et al.
    Luleå tekniska universitet.
    Kaplan, Alexander
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Magnusson, Claes
    Powell, John
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    The effect of process speed on energy redistribution in deep penetration CO2 laser welding2000In: High Temperature Material Processes, ISSN 1093-3611, E-ISSN 1940-4360, Vol. 4, no 2, p. 213-225Article in journal (Refereed)
    Abstract [en]

    This work discusses energy absorption mechanisms in CO2 laser welding and how they are affected by changes in the process speed. Two main energy absorption processes govern the welding interaction: 1. Fresnel absorption at the keyhole walls. 2. Absorption by the partially ionised metal vapour (or plasma) in the keyhole (laser energy absorbed in this way is re-radiated or conducted to the keyhole walls). A theoretical model of these absorption mechanisms has been developed and shown to agree closely with experimental results. Fresnel absorption has been identified as being dominant over plasma absorption and becomes even more influential as welding speeds are increased

  • 33. Lampa, Conny
    et al.
    Kaplan, Alexander
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Powell, John
    Magnusson, Claes
    An analytical model of laser keyhole welding1997In: Proceedings of the 6th Nordic Laser Material Processing Conference, Luleå, Sweden, August 27-29, 1997 / [ed] Claes Magnusson; Hans Engström, Luleå: Luleå tekniska universitet, 1997, p. 218-225Conference paper (Refereed)
  • 34.
    Lampa, Conny
    et al.
    Luleå tekniska universitet.
    Kaplan, Alexander
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Powell, John
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Magnusson, Claes
    An analytical thermodynamic model of laser welding1997In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 30, no 9, p. 1293-1299Article in journal (Refereed)
    Abstract [en]

    An earlier model of deep-penetration laser welding has been simplified in order to provide a useful model of process analysis. This work involves the modelling of the various energy-absorption mechanisms which determine the keyhole shape and thus the dimensions of the melt pool. The penetration depth and weld width (top and bottom) predicted by the model are shown to be in close agreement with experimental results. The widening of the top of the weld seam as a result of Marangoni flow is accurately modelled by introducing an artificially enhanced value for the workpiece's thermal conductivity towards the top of the weld. The model allows analysis of the dependence of the weld profile on the process parameters

  • 35.
    Lampa, Conny
    et al.
    Luleå tekniska universitet.
    Powell, John
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Magnusson, Claes
    Laser welding of copper to stainless steel1997In: Proceedings of the Laser Materials Processing Conference : November 17-20, 1997, San Diego, CA / [ed] Rémy Fabbro, Orlando, Fla: Laser institute of America , 1997Conference paper (Refereed)
    Abstract [en]

    This paper investigates the possibility of CO2 laser welding austenitic stainless steel to copper. The experimental results show that solidification cracking may be the greatest problem in this application. It is suggested that the cracks are generated in three ways: Liquid metal embrittlement, due to the presence of copper in the solidifying steel grain boundaries. Stresses generated during solidification due to fixturing and differences in the thermal properties of the materials involved. A solidification mode change due to the rapid weld solidification involved in laser welding of austenitic stainless steel. To overcome these problems the fixturing and specimen edge preparation have to be optimized to minimize the amount of copper in the fusion zone, to reduce the stresses, and to minimize the cooling rate during solidification. These factors were taken into account and the resulting welds were of high integrity with the same strength as the original copper being welded. The role of thermocapillary or Marangoni flow in transferring heat to the copper side of the weld is also discussed

  • 36.
    Li, W-B
    et al.
    Luleå tekniska universitet.
    Engström, Hans
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Powell, John
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Tan, Z.
    Magnusson, Claes
    Modeling of the laser cladding process: preheating of the blown powder material1995In: Lasers in engineering (Print), ISSN 0898-1507, E-ISSN 1029-029X, Vol. 4, no 4, p. 329-341Article in journal (Refereed)
    Abstract [en]

    Laser cladding is a high precision method of improving the wear and corrosion resistance of metal surfaces. The process gives high quality, porosity free surface layers, with low dilution of the substrate material and with excellent bonding to the substrate. Most frequently metal powder is used as cladding material and there are basically two different methods of application: i) a pre-placed bed of powder on the substrate surface; ii) powder blown into the beam-substrate interaction zone by an inert gas stream, The blown powder cladding process is much more flexible with respect to surface geometries and is therefore the most frequently used method in industry and the subject of this paper. As the blown particles travel through the laser beam on their way to the laser-substrate interaction zone they become heated. This paper gives the results of a theoretical model which investigates the level of pre heating experienced by the particles and the effects of various parameters on this pre heating. The results are important, as the powder particle temperature is expected to be an important parameter in the modelling and control of the cladding process.

  • 37.
    Li, W.-B
    et al.
    Luleå tekniska universitet.
    Engström, Hans
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Powell, John
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Tan, Z.
    Magnusson, Claes
    Redistribution of the beam power in laser cladding by powder injection1996In: Lasers in engineering (Print), ISSN 0898-1507, E-ISSN 1029-029X, Vol. 5, no 3, p. 175-183Article in journal (Refereed)
    Abstract [en]

    In the process of cladding by using blown powder, the laser light passes through the injected powder and is incident on the surface of the substrate. As a result of the presence of the powder cloud there will be a reduction in the laser beam irradiance experienced by the melt pool below it. This effect will be more pronounced where the cloud is at it's deepest. The original laser power density distribution will therefore be altered by passage through the powder stream. The present paper quantitatively describes this phenomenon and suggest some equations by which the redistribution of the power density of the laser beam through the powder cloud can be evaluated. The significance of the redistribution of the laser beam and its possible effect on the temperature in the substrate is also discussed.

  • 38. Magnusson, Claes
    Assessment and competing technologies1998In: Handbook of the Eurolaser Academy, London: Taylor and Francis Group , 1998, p. 577-620Chapter in book (Other academic)
    Abstract [en]

    Factors to be considered in the selection of a laser process and system for a particular application are examined. Various competing technologies are evaluated together with their advantages and limitations in comparison with laser cutting. The operating features, capabilities and applications are discussed for abrasive water jet machining, ultrasonic machining, electrical discharge wire cutting, EB welding, EB cutting and drilling, and plasma arc cutting. The selection, testing, evaluation and control of laser machines are described. Economics are also considered for installation, operation and maintenance.

  • 39. Magnusson, Claes
    Laser materials processing in the Nordic countries1996In: International journal of materials & product technology, ISSN 0268-1900, E-ISSN 1741-5209, Vol. 11, no 3-4, p. 271-275Article in journal (Refereed)
    Abstract [en]

    This article reviews the current state of laser materials processing in the Nordic countries. The effects of the recent recession are shown to have depressed machine tool investment in Europe, but the numbers of lasers continues to grow. Metal cutting is the predominate use for high-power carbon-dioxide lasers, although welding accounts for 20% of the carbon-dioxide lasers installed in the Nordic countries. Welding is predicted to be the fastest growing application area over the next few years for carbon-dioxide lasers. High-power Nd:YAG lasers are used predominately for welding.

  • 40. Magnusson, Claes
    et al.
    Borgström, Robert
    Luleå tekniska universitet.
    Birk, Wolfgang
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering.
    Wiklund, Greger
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Folz, Gerhard
    Jacobi, Martin
    Closed loop temperature control in a laser surface hardening process with CO2-laser1994Report (Other academic)
  • 41. Magnusson, Claes
    et al.
    Rask, Kjell
    Laser workstation for computer-integrated manufacturing1992In: Robotics and Computer-Integrated Manufacturing, ISSN 0736-5845, E-ISSN 1879-2537, Vol. 9, no 4-5, p. 391-393Article in journal (Refereed)
    Abstract [en]

    The application of laser processing technology is rapidly increasing in manufacturing. The laser manufacturing process has since its introduction been computer controlled. At first, the laser was usually a stand alone machine, but recently the demand for its integration with other manufacturing equipment has been stressed. In most respects a laser workstation uses the same interfaces as any other manufacturing equipment. This paper covers some of the integration problems to be solved that are of specific importance for laser workstations.

  • 42. Magnusson, Claes
    et al.
    Tan, Zheng
    Luleå tekniska universitet.
    Mathematical modeling of V-die bending process1990In: Sheet metals in forming processes: 16th biennial congress IDDRG, open sessions, Borlänge, June 11 - 13, 1990 ; congress proceedings, reports, posters, Borlänge: Materials Center, HTM , 1990, p. 363-370Conference paper (Refereed)
    Abstract [en]

    V-die bending is a non-steady state forming process, in which bending moment varies during forming; stress--strain distribution differs in different cross-sections of a bend. By assuming that an isotropic-hardening von Mises material undergoes plane bending, the moment of internal stresses is expressed as a function of the curvature of the bend, sheet thickness and properties of the material. With the constitutive equations given, one can calculate the configuration of a sheet metal in bending and predict its elastic springback on removing load. The theoretical results have been compared to the experimental data, and good agreement has been found. Materials were: DRQ 1147, DOCOL 220, DOCOL 260, and SIS 2322. Graphs. 10 ref.--AA

  • 43. Magnusson, Claes
    et al.
    Wiklund, Greger
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Vuorinen, Esa
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Engström, E.
    Pedersen, T.F.
    FORCES Institute.
    Creating tailor-made surfaces with high power CO2-lasers1991In: Proceedings of the first ASM Heat Treatment and Surface Engineering Conference in Europe: held May 22nd-24th, 1991, in Amsterdam, the Netherlands, Trans Tech Publications Inc., 1991, p. 443-458Conference paper (Refereed)
  • 44. Magnusson, Claes
    et al.
    Öhman, Ulla
    Luleå tekniska universitet.
    Superplastic forming of sheet metal1990In: Sheet metals in forming processes: 16th biennial congress IDDRG, open sessions, Borlänge, June 11 - 13, 1990 ; congress proceedings, reports, posters, Borlänge: Materials Center, HTM , 1990, p. 247-254Conference paper (Refereed)
    Abstract [en]

    Superplastic forming of sheet metal enables forming of complicated details in one step. The forming is done at very low strain rates, making the process slow and cycle times very long. By shortening the cycle time, it should be possible to decrease the unit cost of production and, as a result, superplastic forming would be a highly competitive forming method for new areas of application. A number of methods to shorten the cycle time are presented. Materials considered were Al 7475, Supral 100, and Cr--Ni steel Avesta 223 FAL.

  • 45.
    Meijer, J.
    et al.
    Luleå tekniska universitet.
    Magnusson, Claes
    Wei, L-Y
    Sarady, Istvan
    Phase transformations by high-intensity sub-microsecond laser pulses.1992In: Proceedings of the laser materials processing symposium, ICALEO '92,: [October 25 - 29, 1992, Orlando, Florida, U.S.A.] / [ed] Dave Farson; William Steen; Isamu Miyamoto, Orlando, Fla: Laser institute of America , 1992, p. 228-236Conference paper (Refereed)
    Abstract [en]

    In certain alloys, the 'laser shocking' causes work hardening, an increase in dislocation density and phase transformations. Of the materials tested, and austenitic Hadfield manganese-alloyed steel target was found to have the strongest tendency for a martensitic phase transformation. In contrast with conventional transformation hardening, there is no tempering in the case of repeated application. Whilst most material is vaporized, some surface melting will occur. The rate of re-solidification of the molten material is such that an almost completely amorphous structure results. The martensitic transformation has been confirmed by using optical, scanning and transmission electron microscopy, OM, SEM and TEM/STEM. Two different lasers, a Q-switched Ruby and a Q-switched Nd:YAG were used for the experiments. Calculations of impact/momentum, peak pressure and peak temperature were performed using the finite difference method. The model used for simulating the process has been proved to be useful in understanding the transformation mechanism.

  • 46.
    Nilsson, Annika
    et al.
    Luleå tekniska universitet.
    Melin, Lars
    Luleå tekniska universitet.
    Magnusson, Claes
    Finite-element simulation of V-die bending: a comparison with experimental results1997In: Journal of Materials Processing Technology, ISSN 0924-0136, E-ISSN 1873-4774, Vol. 65, no 1-3, p. 52-58Article in journal (Refereed)
    Abstract [en]

    A major problem in sheet bending is to compensate for springback. Analytical descriptions are not sufficiently general to accommodate influences from the material and the geometry due to the simplifications that have to be made. Practical experiments are still needed to be able to compensate for springback. The aim of this work has been to test the finite-element method on its abilities to predict springback for free bending in a V-die. The work shows that the finite-element method can be used to predict springback off-line. The true stress-true strain curve from a tensile test is used as the material description. Springback has been studied for eight different materials of varying thickness. The process has been simulated with the code Nike2d and the results from the simulations compared with those from experiments, good correlation between the simulations and the experiments being achieved.

  • 47.
    Nilsson, Klas
    et al.
    Luleå tekniska universitet.
    Magnusson, Claes
    Heyden, Johan
    Luleå tekniska universitet.
    Svetsning med pulsad laser1989Report (Other academic)
  • 48.
    Nilsson, Klas
    et al.
    Luleå tekniska universitet.
    Magnusson, Claes
    Tapper, L.
    Outokumpu Copper.
    Bengtsson, A.
    Valeo Engine Cooling.
    Laser welding: a method for welding new designed brass tubes1993In: Working together for a better future: ISATA proceedings; 26th International Symposium on Automotive Technology and Automation, Aachen, Germany, 13th - 17th September 1993: Dedicated Conference on Mechatronics, Croydon: Automotive automation , 1993Conference paper (Refereed)
    Abstract [en]

    In this work, two different tube designs for radiators have been laser welded. In the first phase of the project, a single tube was welded. In a second phase, a special design twin tube was welded. Both tube types had a V-joint, which made it possible to laser weld with high speed. The single tube was formed in a converted lock seam tube machine and the twin tube in a new, for this purpose, special designed tube machine. Both forming machines were integrated with a 5-axis laser work station. In the first phase of the project, a more precise joint geometry was found out, which resulted in the new twin tube design. The second phase with the new tube machine has recently started, and will optimize the welding results from the first phase of the project. All welding experiments have been done on brass (CuZn30). This material is normally used for automobile radiators.

  • 49.
    Nilsson, Klas
    et al.
    Luleå tekniska universitet.
    Magnusson, Claes
    Tapper, L.
    Olsson, K.
    A novel method of joining thin tubes1991In: EUROJOIN 1: 1ère Conférence Européenne sur les Technologies d'Assemblage - First European Conference on Joining Technology, 5-6-7 Nov. 1991, Strasbourg, France ; communications / ECCW, Institut de Soudure , 1991, p. 253-261Conference paper (Refereed)
    Abstract [en]

    Radiator tubing formed from brass strip, with wall thicknesses from 0.09-0.120 mm (0.0035-0.0047 in.), has been successfully welded at high welding speed using a CO sub 2 laser. A fully penetrated weld was obtained using welding speeds of > 100 m/min (5.47 ft/s) in production like conditions. The laser used for the welding was a 1700 W, Co sub 2 laser with linear polarisation. A tube with a specially designed "Y" joint was formed in a converted lock seam tube machine. There are several advantages to this new type of "Y" joint, such as higher production rate and the possibility of reducing the thickness of the brass strip by 20-30% when compared to material used in high frequency welding. A large number of parameters were studied including the effects of laser power, welding speed, joint geometry and direction of the laser beam polarisation. Two radiators have been made with solder coated, laser welded tubes. These are currently undergoing mechanical testing. Preliminary results of the testing are favourable.

  • 50. Ohlsson, L.
    et al.
    Powell, John
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Ivarson, Anders
    Luleå tekniska universitet.
    Magnusson, Claes
    Comparison between abrasive water jet cutting and laser cutting1991In: Journal of laser applications, ISSN 1042-346X, E-ISSN 1938-1387, Vol. 3, no 3, p. 46-50Article in journal (Refereed)
    Abstract [en]

    This paper is intended to demonstrate the advantages and disadvantages of laser profiling techniques as compared with the Abrasive Water Jet (AWJ). The growth of AWJ as a cutting tool has provided engineers with a new profiling technique which often offers great technical and commercial advantages over more traditional methods. However, AWJ cutting is not the best solution to all profiling problems. There are a number of techniques which compete with or complement the process and the optimum profiling method can be difficult to identify. The following paper serves as a general guide-line comparing two competitive cutting methods (CO2 laser cutting and Nd: YAG laser cutting) with AWJ cutting. The subject of cutting covers a great many more processes than can be reviewed in one article but the techniques to be discussed were chosen because they all involve profiling using an axially symmetric energy beam of some sort

12 1 - 50 of 70
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf